Depletion of stratospheric ozone will lead to an increase in solar ultraviolet radiation (UVR) reaching the Earth's surface. The type of UVR that will increase is the so-called UV-B radiation (280-320 nm) which is known to be biologically damaging. The increased levels of UVR will undoubtedly result in an increase in the number of human skin cancers. Based on results of previous animal carcinogenesis studies, it should be possible to use DNA damage as a biochemical marker for use in epidemiological studies to predict increased levels of skin cancer associated with decreased levels of stratospheric ozone. The information obtained from the proposed research will be essential in determining increased levels of epidermal DNA damage in individuals of various skin types as a function of a given ozone depletion. Specifically, we wish to determine: 1) the effectiveness of wavelengths in the UV-B region in inducing DNA damage in the skin of individuals of skin types I-V as classified by sensitivity to the sun and tanning response; and, 2) use solar simulators to mimic UVR transmission associated with various levels of ozone depletion to determine whether the action spectra generated in aim 1 can, in fact, be used to predict increased levels of DNA damage that will occur as a result of ozone depletion.